The monolithic LCD projector refers to a projector product that amplifies and projects an image of a light valve onto a screen through a projection lens based on Kohler illumination by using a full-color transmission type LCD screen as the light valve. The existing monolithic LCD projectors are classified into a direct projection type monolithic LCD projector and a reflection type monolithic LCD projector according to their optical path structures. The direct projection type monolithic LCD projector is rarely seen in the market because of its larger shape, low volume utilization rate and outdated appearance. For the reflection type monolithic LCD projector, such as a monolithic LCD projector disclosed in a Chinese Patent Application No. 201810522555.0. The length of the projector is significantly reduced while the width of the projector is basically constant, so as to reduce the useless space inside the projector. Under the same conditions, the volume of the projector is smaller. However, the LCD light valve has poor heat radiation performance, and very high requirements for the coating performance of the reflector; otherwise, the reflector has poor reflection performance, resulting in poor color uniformity of the image projected onto the screen, affecting the image quality and limiting the practical effect.